>> yeah, about two years ago the fbi was investigating tamerlan. they had a tip from an overseas government that he had been radicalized and he had become a follower of radical islam. so they opened an investigation. they asked him questions. they checked phone records, but they discovered that it didn't appear that he was a threat. pretty remarkable. >> all right. tamon, thank you very much for joining us this morning live from boston. abc's this week with george stephanopoulos had a special edition this morning focusing on the boston bombings. surviving suspect, dzhokhar darn, is not capable of talking to investigators because of wounds to his neck and throat. as to why they plan to question him without first reading his miranda rights, here's what sources tell abc news senior justice correspondent, mr. thomas. >> taking an extraordinary step because there could be an imminent threat out there. they said there's deep, deep concern about the amount of ammunition, guns and work being bombs these men had. they were so disciplined. >> but any evidenc